The altitude of USA 310 (20083A / 46918) has been gradually increasing since early January. This is evident in hobbyist and ISON elements published weekly by JSC "Vimpel Interstate Corporation”. The mean motion was nearly constant from epoch 20350 through epoch 21004, but has been gradually decreasing ever since. During Feb 23 to Mar 01, ndot/2 was -0.00000234 rev/d^2, on average. Comparison with the result of orbit propagation using GMAT 2018a confirms that the evolution of the inclination and RAAN is as expected in the presence of Earth's gravity and lunisolar perturbations. But this is not true of eccentricity, argument of perigee, and mean motion. SRP (solar radiation pressure), appears not to explain the orbital changes. This is based on GMAT propagations based on a sphere, with various area to mass ratios. No attempt was made to analyze more complex SRP spacecraft geometry and orientation. Since the eccentricity has remained fairly constant, I suspect that the spacecraft has been manoeuvring to a higher orbit. However, the rate of climb has been extremely slow, so it is not going anywhere fast. Perhaps the changes are minor tweaks of the orbit. I am interested in alternative explanations. The following TLE has been fit to ISON/Vimpel position vectors, following conversion from J2000 to TEME. USA 310 11074 X 11099 km 1 46918U 20083A 21060.96907407 .00000000 00000-0 00000-0 0 05 2 46918 58.4983 277.6711 0007177 278.8114 81.1597 3.76151888 09 Ted Molczan _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-lReceived on Sat Mar 13 2021 - 09:29:19 UTC
This archive was generated by hypermail 2.4.0 : Sat Mar 13 2021 - 15:29:19 UTC